# Proposed AD 97-SW-61-AD: McDonnell Douglas Helicopter Systems Model 369D, 369E, 369FF, 369H, MD500N, and MD600N Helicopters

- Type: Proposed airworthiness directive (not in force)
- Status: Became AD 99-04-12
- Action: Notice of proposed rulemaking (NPRM).
- Published: May 15, 1998, 63 FR 27011
- Comments due: July 14, 1998
- Became: [AD 99-04-12](https://openairdocs.org/ad/99-04-12)
- Docket: 97-SW-61-AD
- FR document: 98-12936
- Official PDF: https://openairdocs.org/files/sha256/35/d4/35d4a7f28ca8a2d99b3dd3f1af5d225ae7bf1e23de2e592c58905f7d241ea8cf (from https://www.govinfo.gov/content/pkg/FR-1998-05-15/pdf/98-12936.pdf)
- Federal Register: https://www.federalregister.gov/documents/1998/05/15/98-12936/airworthiness-directives-mcdonnell-douglas-helicopter-systems-model-369d-369e-369ff-369h-md500n-and
- Page: https://openairdocs.org/proposed/97-SW-61-AD

## Summary

This document proposes the adoption of a new airworthiness directive (AD) that is applicable to McDonnell Douglas Helicopter Systems (MDHS) Model 369D, 369E, 369FF, 369H, MD500N, and MD600N helicopters. This proposal would require a one-time visual inspection of certain input shaft coupling assemblies for pitting. This proposal is prompted by three operators' reports of discovering pitting on the internal spline teeth. The actions specified by the proposed AD are intended to prevent failure of the spline teeth in the input shaft coupling assembly, loss of drive to the main rotor system, and subsequent loss of control of the helicopter.

## Notices in this docket

- May 15, 1998: Notice of proposed rulemaking (NPRM). (first notice), FR document 98-12936, comments due Jul 14, 1998 (https://www.federalregister.gov/documents/1998/05/15/98-12936/airworthiness-directives-mcdonnell-douglas-helicopter-systems-model-369d-369e-369ff-369h-md500n-and)

---
OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.